"The emergency level 1 of this dam will be triggered without the need for ZAS (self-rescue zone) evacuation," the miner said.

Six deactivated upstream dams at emergency levels 2 and 3 still had negative DCEs, Vale said, adding their self-rescue zones had already been evacuated.

It said the Vargem Grande dam's emergency level was reduced from 2 to 1 in June and it still had a negative DCE.

A further nine structures kept their negative DCEs, including Dam VI at the Córrego do Feijão mine, Vale said.

The miner has earmarked R$7.1 billion (US$1.7 billion) to "de-characterise" its upstream tailings dams since the fatal collapse of the B1 dam at Córrego do Feijão at Brumadinho in January which killed about 250 people, with a further 21 still listed as missing.

Police last month formally accused seven individuals from Vale and six from German safety inspector TÜV SÜD, for covering up structural dangers at the dam during safety audits only months before it ruptured.

"Given the Resolution 13 of the National Mining Agency (ANM), published in August this year, and the new parameters established, Vale is working with its technicians and specialists in complementary analysis and in planning new measures to increase safety factors in order to ensure the stability of its structures," the company said.

It said its 2019 iron ore and pellets sales were expected to be around the centre of its revised forecast of 307-332 million tonnes.